The present invention relates to an apparatus and method of automatically inspecting and rejecting glass articles during their manufacture. Such apparatus and method may be used on a variety of different types of glass forming machines provided that the glass article produced is suspended from a fixed point after it leaves the mold; retains some residual heat from the molding operation; and that the top of the glass article is visible. The present invention is particularly useful during the manufacture of hollow glass articles on what is commonly referred to as a glass ribbon machine. In a preferred application, the present invention relates to automatically inspecting incandescent lamp envelopes produced on a ribbon machine and rejecting such envelopes if they are too short or their tops are too thin or too thick.
Glass ribbon machines are well known in the art, one of the earliest being described in U.S. Pat. No. 1,790,397 issued to W. J. Woods et al., and incorporated herein by reference. Such glass ribbon forming machines typically provide for formation of a stream of molten glass into a ribbon of glass which is laid upon an endless chain of orifice plates. Such endless chain and ribbon of glass supported thereon are conveyed in a linear manner through various process steps the last of which involves severing each hollow glass article from the linearly travelling ribbon of glass. In the manufacture of incandescent lamp envelopes, hollow glass envelopes so produced are separated from the linearly travelling ribbon of glass and subjected to further process steps including cleaning and treatment of the interior of each envelope, insertion of the lamp element and sealing of the envelope.
Other known ribbon forming machines include U.S. Pat. No. 1,833,284 issued to Gray, U.S. Pat. No. 3,647,410 issued to Heaton et al. and U.S. Pat. Nos. 3,642,461 and 3,775,084 issued to Heaton, each incorporated herein by reference.
The operation of a ribbon machine to produce lamp envelopes or bulbs is a high speed process typically providing for the production of in excess of one thousand bulbs per minute. Due to such high speed, bulb inspection is usually done on a sampling basis after manufacture of the bulbs and before further processing thereof. For example, in one known inspection technique, bulb sampling is done manually, the bulbs selected being gauged by hand. If any of the bulbs are too short or have tops which are too thick or too thin, all of the bulbs coming down the production line are rejected until another test is conducted which indicates that there are no defective bulbs. Such an inspection process is costly, resulting in scrapping the good as well as the defective bulbs produced between such tests. In addition to adding to manufacturing costs, most of the bulbs are shipped to the customer without being inspected; that is, when a test is conducted, if the test sample results in no defective bulbs, all of the bulbs which come down the production line are further processed and shipped to customers until such time as a test is conducted which indicates that there are defective bulbs.
It is believed that at least one bulb manufacturer using the ribbon forming method inspects the bulbs by means of a laser and detector apparatus for detecting and rejecting short bulbs. However, such system is not believed to be effective in detecting and rejecting bulbs having tops which are too thin or too thick.
It is also known to use a blank length detector to inspect for short bulbs on a ribbon machine. In particular, a line scan camera is provided to detect the length of the blank. However, the effectiveness of this technique is limited in that a short bulb is not always caused by a short blank. In addition, this system is also not effective in detecting and rejecting bulbs having tops which are too thin or too thick.
It is an object of this invention to provide an improved apparatus and method of automatically inspecting glass articles during their manufacture.
It is also an object to provide an apparatus and method of automatically inspecting hollow glass articles during their manufacture on a glass ribbon machine to determine whether any of such hollow glass articles are too short or have tops which are too thin or too thick.
It is a still further object to provide an apparatus and method of automatically inspecting each hollow glass article produced by a glass ribbon machine and automatically rejecting any such hollow glass article which is too short or has a top which is too thin or too thick.
It is also an object to provide an apparatus and method of automatically inspecting and rejecting glass articles, during their manufacture, which is not labor intensive.
It is a further object to provide an apparatus and method of automatically inspecting and rejecting glass articles during their manufacture without rejecting the good glass articles along with the defective glass articles.
It is yet another object to provide an apparatus and method of automatically inspecting and rejecting hollow glass articles during their manufacture on a glass ribbon machine while such hollow glass articles are still on the ribbon of glass.